Although strict adherence to antiretroviral therapy (ART) is required to achieve health benefits of treatment, there are no known interventions that have improved ART adherence among young Black men who have sex with men (YBMSM). Novel, sustainable interventions that improve adherence to ART among HIV+ YBMSM are needed to improve individual health, decrease health care costs, and reduce HIV transmission risk. The overall objective of the proposed research is to design a novel mobile phone application (app) utilizing game mechanics and social networking features to improve and optimize the durability of ART adherence among YBMSM ages18-29. The rationale that drives the proposed research is that innovative approaches that utilize widely available technology and are engaging, interactive, tailored and theory driven are more likely to improve ART adherence among YBMSM than existing interventions. Data demonstrating high levels of access to and use of mobile phones among YBMSM points to the importance of using tools based in these technologies. The proposed SBIR Phase I research has three specific aims: 1) Formative research: Conduct focus groups to better understand the ART information, motivation and behavioral skills needs of the target population and identify the best strategies for addressing these needs through the mobile game app; 2) Technology development: Develop the smartphone app (Daily Dose, or 2D) based on the Information, Motivation, and Behavior Skills model of ART adherence supplemented by gamification principles; and 3) Usability testing: Test the intervention with an internal testing group and members of the target population to identify any potential problems with the mobile game app and allow for optimization of the intervention. The proposed research is innovative because it will develop a mobile game app that uses a wide range of smartphone features to create an ART adherence intervention for HIV+ YBMSM that is individually tailored, highly interactive and engaging, provides opportunities to learn important self-management skills related to medication adherence and is highly relevant in today's world and the lives of YBMSM. This research is significant because it will address a critical need for effective ART interventions for HIV+ YBMSM that is delivered through a widely utilized technology medium and uses a game approach, which is expected to be highly appealing and engaging for the targeted population. Moreover, the creation of a novel technology based adherence tool could be easily adapted for other highly prevalent and costly chronic diseases that require consistent medication adherence. Key indicators of success in Phase I include: functional prototypes of the 2D app and mock- up representations of other app features; usability test results; and an action plan for Phase II.